Filter tube



D. MILLER, JR

FILTER TUBE Jul 31, 1%:

2 Sheets-Sheet 1 Filed June 17, 1949 l 0 O E z 5 x a H 0 I- a /fl., fl 'l I! lllllll 7 7 3 8 B u uA 1 INVENTOR.

aux-121F111 fl D. MILLER, JR

July 31, 1951 FILTER TUBE 2 Sheets-Sheet 2 Filed June 17, 1949 a 6 an J m 4 a W IN VEN TOR.

BY W;

A Z Z/W5 Patented July 31, 1951 FILTER TUBE Durando Miller, Jr., Pelham Manor, N. Y., as-

signor to The Permutit Company, New York, N. Y., a corporation of Delaware Application June 17, 1949, Serial No. 99,634 1 Claim. (Cl. 2l0184) This invention relates to filters of the type having foraminous means and employing as the filtering material diatomaceous earth deposited on said foraminous means, and more particularly to the construction of said foraminous means.

Filters of such type have become well known, and reference is made, by way of an example, to the U. S. Patent 2,423,172 of George Martin Booth, dated July 1, 1947, which discloses a filtering apparatus on which my invention is an improvement.

It is the object of my invention to provide improved foraminous means adapted for more efilcient operation and which are foldable prior to removal from the filter so as to reduce the headroom required in the building in which the filter is installed.

The manner in which this object is achieved is shown in the accompanying drawings in which- Fig. 1 shows an apparatus in accordance with my invention in elevation, partly in section;

Fig. 2 is a fractional plan view of the-apparatus with the domed cover 15 removed; and

Fig. 3 is an elevational view on an enlarged scale and partly in cross section of two filter tube assemblies, one being in place on the tube sheet and the other being shown in partly folded condition during removal from the filter.

Similar numerals refer to similar parts throughout the several views.

The apparatus comprises a tank In with a cylindrical side H and a dished bottom l2 to which is attached a pocket l3. To the top of the cylindrical portion H is welded a tube sheet 14. Over the tube sheet [4 is fitted a domed cover l5 attached to the tube sheet M by means of a flange l6 and bolts and nuts ll. The space within tank 18 and below the tube sheet [4 forms an infiuent chamber I8, and the space within the domed cover I5 and above the tube sheet l4 forms an efiluent chamber IS.

A pump 20 is provided with a suction pipe 2! receiving the liquid to be filtered and with a discharge pipe 22 fitted with a valve 23 and leading to the pocket l3. A branch 24 of the discharge pipe 22 is provided with a valve 25 and terminates in a bent portion 25 within the infiuent chamber l8 adjacent to the dished bottom l2. Leading from the lowest part of the pocket I3 is a drain pipe 28 fitted with a valve 28. A funnel 3| is provided for the introduction of filter aid and connected with the infiuent chamber l8 by a pipe 32 provided with a valve 33. A pipe 35 leads from a point as high as possible within the influent chamber l8 through a quick-opening valve 36 to the outside. An outlet pipe 38 leads from the efiluent chamber 19 through the cover l5, as shown, and has a branch 39 provided with a valve 48 and leading to a point of use, and another branch 4| provided with a valve 42 and leading to a point of waste. The pipe 38 also communicates with an air vent comprising a cook 43 having therein a fiow restricting passage 44. A sump 46 is arranged to receive the discharges from pipes 28 and 4| and lead them to a point of disposal through a pipe 41.

The tube sheet 14 carries a number of identical filter tube assemblies, each referred to as a whole by the numeral 50. Each such filter tube assembly 58 comprises a support plate 5| which rests against the tube sheet l4 with an interposed gasket 52 and which is provided with openings 53. The plate 5| has an integral sleeve 54 on which is mounted a stack of Ioraminous filter elements 63 made of sintered bronze balls and rabbeted, as shown at 64, to each other, to the sleeve 54, and to a bottom plate placed against the lowermost filter element 63. The interstices between the beads forming the filter elements 83 advantageously range in size from about 0.001 to 0.002 inch so that they are readily bridged over by the filter aid. A flexible member such as a cable or chain 61 connects the bottom plate 68 with a partly threaded rod 58 passing through a bore 56 which extends through the plate 5i and a boss 55 thereon. A pin 51 press fitted into the boss 55 extends into a groove 59 in the side of the threaded rod 58 so as to prevent rotation but permit axial movement of the threaded rod 58 within the bore 56. A wing nut 68 is provided to place the chain 61 in tension so as to rigidly clamp the stack of filter elements 63 between the sleeve 54 and the bottom plate 66. A screw St at the end of rod 58 provides a stop to prevent unintentional removal of the wing nut 88 from the rod 58 which would permit the rod 58, the chain 61, the bottom plate 65 and the filter elements 63 to drop to the bottom of the inlet chamber l8 whence it would be difiicult to retrieve them.

Fig. 3 shows a filter tube assembly 58 mounted on the tube sheet l4 and ready for operation, being held in place by clamps 89 which are fastened by nuts 10 on studs 1 I. Another filter tube assembly 58' is shown in a folded state during replacement or removal which may become necessary after prolonged operation, for the purpose of replacing Or mechanically scrubbing the filter elements 53. After removal of the bolts and nuts H the domed cover l5 may be lifted off, making the tops of the filter tube assemblies 58 accessible.

- 3 Upon unscrewing nuts HI and lifting on clamps 36 each filter tube assembly may be withdrawn upwardly. In many cases. however, it is desirable in the interest oi economy to install the filter in a space which afiords insufilcient head room to permit upward withdrawal of the filter tube assembly 60. In that event the filter tube assembly 66 (Fig. 3) may be folded during removal. The wing nut 63 is unscrewed until it comes up against the stop screw 6| This places enough slack on the chain 61 to permit breaking any one of the rabbeted Joints 84 between the sleeve 64 and the stack of elements 63. or between any two adjoining elements 63, as clearly illustrated in Fig. 3. In this manner the filter tube assemblies 50 may be readily removed from the apparatus even though there is Just enough head room to accommodate the assembled apparatus. The outlet pipe 33 can, of course, be shortened or be arranged to pass through the side instead of the top of the domed cover I! in order to further reduce the required head room.

The apparatus shown in Fig. 1, together with the following method of backwashing the filter elements, is the subject matter of a co-pending application of Norman Cooperson and A. W. Kingsbury Ser. No. 99,602, filed June 17, 1949.

In operating the apparatus the valves 33 and 42 are opened, all other valves being closed, and a quantity of filter aid is introduced as a slurry into the empty tank l6 through the funnel 3| and pipe 32, and drops onto the dished bottom l2 and into the pocket [3. Valve 33 is then closed and pump 23 started, with valves 23 and 25 open. The incoming liquid fills the tank l0, stirs up the filter aid and carries it upward to be deposited as a layer against the filter elements 63, forming the so-called precoat. The discharge from the bent portion 26 of pipe 24 helps to stir up all filter aid resting on the bottom 12 and to suspend it in the up-fiowing water. During this filling operation. air is discharged through the outlet pipe 33. valve 42, and pipe 4!.

As the apparatus is being filled with water, air remains trapped in the infiuent chamber l3 above the level AA and in the effluent chamber it above the level BB. As soon as the liquid has risen to the level BB the discharge of air stops and liquid fiows from pipe 4|. Such liquid is likely to be turbid at first, containing some particles of filter aid, but such turbidity will disappear within about one minute, whereupon valve 40 is opened and valve 42 closed which places the apparatus is normal filtering service, the filtered liquid fiowing via pipe 33 at a point of use. The rate of filtration may be between about 2 and 8 gallons per minute per square foot of area of the foraminous elements 63, depending on the viscosity and turbidity of the liquid to be filtered. With water having a turbidity up to about 10 parts per million I find a rate of about 4 gallons per minute per square foot most satisfactory. With higher rates of flow the quantity of liquid that can be filtered between backwashings becomes less.

As filtration progresses, the turbidity in the liquid is retained by the blanket oi filter aid deposited on the filter elements 63, causing the pressure loss through the filter elements 63 to increase gradually, and when the pressure in the infiuent chamber l3 has reached a predetermined value of somewhere between 10 and 100, say 50 pounds per' square inch, the normal service operation is terminated in order to backwash the 43 and 23 are closed and valves 23 and 42 are opened. The apparatus now drains through the pipe 23, air entering through the pipe 4|. During this draining operation, the Jet or liquid coming in through pipe 24 helps to stir up the contents of the lower portion of the infiuent chamber l3 and flush out all dirt and filter aid dropping from the filter elements 63. As soon as the tank has drained substantially empty valves 23 and 42 are closed and valve 23 is opened. Liquid now enters the tank In, compressing the air as the tank is being filled. As soon as the air within the tank has been compressed to the maximum pressure which the pump 20 can produce, for instance pounds per square inch. the liquid level in tank III will be somewhat below level AA. Now the cock 43 is opened so as to discharge air from the eilluent chamber I! through the fiow restricting passage 44 without permitting the pressure within tank H) to decrease appreciably. As compressed air is thus being discharged, liquid enters until it reaches the level AA, trapping a definite compressed air volume in the infiuent chamber l3 above the level AA. Thereupon, the liquid rises through the filter tube assemblies ll into the eilluent chamber l3 until it reaches the lower end of the outlet pipe 36, that is level BB. Then liquid wil be discharged through the outlet pipe 33, and the cock 43, a second definite volume oi compressed air being thus retained within tank In in the eiiluent chamber l3 above the level BB.

The flow of liquid from cock 43 indicates that the tank has been prepared for the backwashing operation and cock 43 is now closed.

Valves 23 and 25 are then closed and the pump 20 may be shut down if desired. The quick-opening valve 36 is next opened, permitting the compressed air in infiuent chamber II to be exhausted rapidl to atmosphere through pipe 33. The compressed air in eflluent chamber l3 consequently expands rapidly and forces the liquid in the eilluent chamber I9 through the filter elements 63 at a high rate of flow, cleansing them of any remaining filter aid or dirt. This backwash operation takes but a fraction of a second and its end is indicated by the mergence of a small quantity of liquid from the pipe 36. The valve 36 is now closed.

The amount of impurities dislodged during the backwash operation is relatively small. Nevertheless, it is desirable to remove them and this is accomplished by opening valves 29 and 42 to drain the tank 40 preparatory to introducing a new batch of filter aid into the funnel 3i and resuming the cycle of operations as described. During this training operation, the pump 26 need not but may be operated with valve 23 open to more eil'ectively cleanse the lower portion 01 tank ID.

If the liquid being filtered contains relatively large amounts of turbidity it may be advantageous. in the interest of longer filter runs, to continuously add filter aid to the liquid being filtered, ttielrmaii ti body feed, in a manner well understood in While I have disclosed what I consider the preierred embodiment of my invention, modifications may be made without departing from its spirit. and reference is, therefore. made to the appended claim for a definition of the scope of my invention.

What I claim is:

A filter tube assembly comprising a supporting member, a cylindrical. sleeve extending downwardly from said supporting member, a plate, a stack of hollow foraminous fllter elements between said plate and said sleeve, a flexible member located within said stack and said sleeve and having one end attached to said plate, and means,

on said supporting member connected with the other end of said flexible member and adapted to place said flexible member under tension so as to rigidly clamp said stack between said sleeve and said plate, and to release the tension of and im- 6 .anraneneas man The following references are of record in the flle of this patent:

5 UNITED'STATES PATENTS Number Name Date 272,831 Field Feb. 20, 1883 1,040,090 Zahm Oct. 1, 1912 1,246,850 Best Nov. 20, 1917 10 1,263,226 Genter Apr. 16, 1918 1,771,928 July 29, 1930 2,079,475 Williams et a1. May 4, 1937 2,200,899, Scheidt May 14, 1940 3,228,529 Jan. 14, 1941 16 2,300,849 ,Tauch Nov. 3. 1942 Booth July 1, 194'! pert slack to said flexible member suflicient to permit folding said flexible member and said stack.

DURANDomm-h. 

